Diagnostic Routine A
Diagnostic Routine A
Diagnostic Overview
Engine Does Not Crank (Without Intelligent Access)
Refer to Wiring Diagram Set 20, Starting System for schematic and connector information. Diagrams By Number
Normal Operation and Fault Conditions
Under normal conditions when the ignition switch is turned to the START position, the BCM (Body Control Module) and PCM (Powertrain Control Module) receive a request to crank the engine. When the PCM (Powertrain Control Module) receives the correct inputs from the BCM (Body Control Module) and notification from the TR (Transmission Range) sensor that the gear selector is in PARK or NEUTRAL, the PCM (Powertrain Control Module) then supplies voltage and ground to the starter relay coil. The energized coil causes the starter relay contacts to close. This allows voltage to be supplied from the BJB (Battery Junction Box) to the starter solenoid coil. The starter solenoid coil is grounded at the starter motor. Energizing the starter solenoid closes the solenoid contacts allowing voltage directly from the battery to the starter motor, engaging the starter drive into the ring gear causing the engine to crank. The PCM (Powertrain Control Module) disengages the starter motor once an engine RPM (Revolutions Per Minute) threshold is reached, a set crank time is exceeded or the ignition switch has been turned to the OFF position.
Visual Inspection and Diagnostic Pre-checks
- Inspect the battery.
- Inspect the battery cables.
- Inspect BJB (Battery Junction Box) fuse 19 (30A).
- Inspect BCM (Body Control Module) fuse 28 (15A).
- Inspect the starter motor.
- Inspect the starter motor bolts.
- Inspect the IKT (Integrated Keyhead Transmitter).
- Inspect the starter relay.
- Inspect high current battery junction box connections.
Pinpoint Test
1. CHECK THE BATTERY
1. Check the battery condition and state of charge. REFER to Diagnostic Routine A: Battery Condition Test Pinpoint Tests.
Is the battery OK?
2. CHECK FOR ANY MESSAGES IN THE MESSAGE CENTER
1. Check the message center while holding the ignition key in the start position.
Is STARTING SYSTEM FAULT displayed in the message center?
3. CHECK THE IN GEAR-TRANSMISSION IS APPLYING A LOAD TO ENGINE (IN_GEAR) PID (Parameter Identification).
1. Using a scan tool, view the PCM (Powertrain Control Module) PIDs (Parameter Identifications).
2. While observing the PCM (Powertrain Control Module) PID (Parameter Identification) IN_GEAR, place the gear selector in PARK and then NEUTRAL.
Does the PID (Parameter Identification) read NO in both positions?
4. RETRIEVE PCM (Powertrain Control Module) DTCs (Diagnostic Trouble Codes)
1. Ignition ON.
2. Using a scan tool, perform the PCM (Powertrain Control Module) self-test.
Were DTCs (Diagnostic Trouble Codes) retrieved on-demand during self-test?
5. CHECK THE ENGINE CRANKING (ENG_CRANK) PID (Parameter Identification)
1. Using a scan tool, view the PCM (Powertrain Control Module) PIDs (Parameter Identifications).
2. While holding the key in the START position, monitor the PCM (Powertrain Control Module) PID (Parameter Identification) ENG_CRANK.
Does the PID (Parameter Identification) change from Inactive to Active?
6. CHECK THE STARTER RELAY
1. Swap the starter relay with a known good relay and attempt to crank the engine.
Does the engine crank?
7. CHECK THE VOLTAGE TO THE STARTER RELAY
1. Ignition OFF.
2. Disconnect: Starter Relay.
3. Measure:
Is the voltage greater than 11 volts?
8. CHECK THE STARTER MOTOR
1. With the gear selector in PARK, connect a fused jumper wire:
Did the starter motor engage and the engine crank?
9. CHECK THE BATTERY GROUND CABLE
1. Measure:
Is the voltage greater than 11 volts?
10. CHECK THE STARTER MOTOR GROUND
1. Measure:
Is the voltage greater than 11 volts?
11. CHECK THE VOLTAGE TO THE STARTER MOTOR
1. Measure:
Is the voltage greater than 11 volts?
12. CHECK THE STARTER MOTOR
1. Connect a fused jumper wire:
Did the starter engage and the engine crank?
13. CHECK FOR START INPUT AT THE STARTER
1. Connect: Starter Relay.
2. Disconnect: Starter Solenoid C197B.
3. While holding the key in the START position, measure:
Is the voltage greater than 11 volts?
14. CHECK THE PCM (Powertrain Control Module) START CIRCUITS FOR A SHORT TO GROUND
1. Ignition OFF.
2. Disconnect: PCM (Powertrain Control Module) C175B.
3. Measure:
Are the resistances to ground greater than 10,000 ohms?
15. CHECK THE PCM (Powertrain Control Module) START CIRCUITS FOR AN OPEN
1. Measure:
Are the resistances less than 3 ohms?
16. CHECK THE START CIRCUIT FOR VOLTAGE AT THE PCM (Powertrain Control Module)
1. Ignition OFF.
2. Disconnect: PCM (Powertrain Control Module) C175B.
3. While holding the key in the START position, measure:
Is the voltage greater than 11 volts?
17. CHECK THE IGNITION SWITCH
1. Carry out the Ignition Switch Component Test.
Did the ignition switch pass the component test?
18. CHECK FOR CORRECT PCM (Powertrain Control Module) OPERATION
1. Ignition OFF.
2. Disconnect and inspect all PCM (Powertrain Control Module) connectors.
3. Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
4. Reconnect the PCM (Powertrain Control Module) connectors. Make sure they seat and latch correctly.
5. Operate the system and determine if the concern is still present.
Is the concern still present?
